Are you making or teaching the piaffe?
As a Grand-Prix rider and horse trainer, I’ve seen many horses do a piaffe.
But only a few of them were properly executed in a way that’s durable to their body.
A piaffe needs to be so natural that it seems like they can do it all day. The movement flows from their willingness to perform.
It’s why it’s so important that you’re teaching a piaffe instead of making it.